CN112687813A - Organic light emitting diode and organic light emitting device including the same - Google Patents

Organic light emitting diode and organic light emitting device including the same Download PDF

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CN112687813A
CN112687813A CN202010995340.8A CN202010995340A CN112687813A CN 112687813 A CN112687813 A CN 112687813A CN 202010995340 A CN202010995340 A CN 202010995340A CN 112687813 A CN112687813 A CN 112687813A
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light emitting
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CN112687813B (en
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J·A·李
金捘演
洪太良
白贞恩
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Abstract

The present disclosure relates to an Organic Light Emitting Diode (OLED) and an organic light emitting device including the same, the diode including a plurality of light emitting material layers disposed between two electrodes and an electron blocking layer, wherein an energy level of the electron blocking layer disposed adjacent to an emission material layer having a relatively low level delayed fluorescent material and an energy level of the delayed fluorescent material are controlled. The OLED can reduce its driving voltage and maximize its light emitting efficiency and light emitting life.

Description

Organic light emitting diode and organic light emitting device including the same
Cross Reference to Related Applications
This application claims priority from korean patent application No. 10-2019-0129776, filed in korea at 18.10.2019, the entire contents of which are incorporated herein by reference.
Technical Field
The present disclosure relates to an organic light emitting diode, and more particularly, to an organic light emitting diode having excellent light emitting properties, and an organic light emitting device including the same.
Background
As display devices become larger, a flat display device having a lower space requirement is required. Among the flat display devices that are currently widely used, Organic Light Emitting Diodes (OLEDs) are rapidly replacing liquid crystal display devices (LCDs).
In the OLED, when charges are injected into an emission material layer between an electron injection electrode (i.e., a cathode) and a hole injection electrode (i.e., an anode), the charges are recombined to form excitons, and then light is emitted as the recombined excitons are converted to a stable ground state. The OLED can be formed to have a thickness less than
Figure BDA0002692335410000011
And may implement unidirectional or bidirectional imaging as an electrode configuration. In addition, the OLED may be formed on a flexible transparent substrate (e.g., a plastic substrate), so that the OLED may easily realize a flexible or foldable display. In addition, the OLED can be driven at a lower voltage of 10V or less. In addition, the OLED has relatively low driving power consumption compared to a plasma display panel and an inorganic electroluminescent device, and the color purity of the OLED is very high. In particular, the OLED can implement red, green, and blue colors, and thus it attracts much attention as a light emitting device.
Conventional fluorescent materials exhibit low luminous efficiency because only singlet excitons participate in their light emission process. Phosphorescent materials in which triplet excitons and singlet excitons participate in the light emitting process have relatively high light emitting efficiency compared to light emitting materials. However, the emission lifetime of the metal complex, which is a typical phosphorescent material, is too short to be used in commercial devices.
Disclosure of Invention
Accordingly, embodiments of the present disclosure are directed to an Organic Light Emitting Diode (OLED) and an organic light emitting device including the OLED that substantially obviate one or more problems due to limitations and disadvantages of the related art.
An aspect of the present invention provides an OLED that reduces its driving voltage and enhances its light emitting efficiency and light emitting lifetime, and an organic light emitting device including the same.
Additional features and aspects will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the inventive concepts presented herein. Other features and aspects of the inventive concept may be realized and attained by the structure particularly pointed out or derived from the written description and claims hereof as well as the appended drawings.
To achieve these and other aspects of the inventive concept as embodied and broadly described, a light emitting diode includes: a first electrode; a second electrode facing the first electrode; a first emissive material layer disposed between the first and second electrodes; a second emissive material layer disposed between the first emissive material layer and the second electrode; and an electron blocking layer disposed between the first electrode and the first emission material layer, wherein the first emission material layer and the second emission material layer each include a first compound and a second compound, wherein the second compound includes an organic compound having a structure of the following chemical formula 1 or chemical formula 3, wherein a level of the second compound in the first emission material layer is higher than a level of the second compound in the second emission material layer, and wherein a HOMO (highest occupied molecular orbital) energy level (HOMO) of the second compoundDF) And a HOMO energy level (HOMO) of the electron blocking layerEBL) Satisfies the relationship in the following formula (1):
0eV<HOMOEBL–HOMODF<0.4eV (1)；
[ chemical formula 1]
Figure BDA0002692335410000021
Wherein R is1And R2Each independently is hydrogen or C1-C20An alkyl group; n is an integer of 0 to 4;
[ chemical formula 3]
Figure BDA0002692335410000031
Wherein R is11And R12Each independently is hydrogen or C1-C20An alkyl group; r13Is unsubstituted or substituted C8-C30Condensed heteroaryl, unsubstituted or substituted C6-C20Aromatic amino group, or unsubstituted or substituted C3-C20A heteroaromatic amino group, wherein the fused heteroaryl group includes at least one of a carbazolyl moiety, an acridinyl moiety, a phenazinyl moiety, and a phenoxazinyl moiety.
In another aspect, an organic light emitting diode includes: a first electrode; a second electrode facing the first electrode; a first emissive material layer disposed between the first and second electrodes; a second emissive material layer disposed between the first emissive material layer and the second electrode; and an electron blocking layer disposed between the first electrode and the first emission material layer, wherein the first emission material layer and the second emission material layer each include a first compound and a second compound, wherein the second compound includes an organic compound having a structure of the following chemical formula 1 or chemical formula 3, wherein a level of the second compound in the first emission material layer is higher than a level of the second compound in the second emission material layer, wherein the electron blocking layer includes an organic compound having a structure of the following chemical formula 5 or chemical formula 7, wherein when the second compound is an organic compound having a structure of the chemical formula 1, the electron blocking layer includes an organic compound having a structure of the chemical formula 7, and wherein when the second compound is an organic compound having a structure of the chemical formula 3, the electron blocking layer includes an organic compound having a structure of chemical formula 5:
[ chemical formula 5]
Figure BDA0002692335410000032
Wherein R is21To R23Each independently is unsubstituted or substituted C6-C30Aryl or unsubstituted or substituted C3-C20A heteroaromatic amino group;
[ chemical formula 7]
Figure BDA0002692335410000041
Wherein R is31Is unsubstituted or substituted C6-C20An aryl group; r32And R33Each independently is hydrogen or unsubstituted or substituted carbazolyl, wherein R32And R33Is a carbazolyl group; r34And R35Each independently hydrogen, unsubstituted or substituted C1-C10Alkyl, unsubstituted or substituted C6-C20Aryl or unsubstituted or substituted C3-C20A heteroaryl group; and p and q are integers of 0 or 1, respectively.
In another aspect, an organic light emitting device includes a substrate and an OLED disposed on the substrate as described above.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the inventive concepts claimed.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the disclosure and together with the description serve to explain the principle of the disclosure.
Fig. 1 is a schematic cross-sectional view illustrating an organic light emitting display device according to an aspect of the present disclosure.
Fig. 2 is a schematic cross-sectional view illustrating an OLED of the present disclosure.
Fig. 3 is a schematic diagram illustrating a light emitting mechanism through an energy band gap between light emitting materials according to the present disclosure.
Fig. 4 is a schematic diagram showing a charge transport problem caused by the HOMO level band gap between the EML and the EBL in one comparative example.
Fig. 5 is a schematic diagram showing a charge trap problem caused by a HOMO level bandgap between the EML and the EBL in another comparative example.
Fig. 6 is a schematic diagram illustrating injection of charges without any charge transport problem or charge trap problem by controlling the HOMO level bandgap between the EML and the EBL in the present disclosure.
Detailed Description
Reference will now be made in detail to aspects, embodiments, and examples of the present disclosure, some examples of which are illustrated in the accompanying drawings.
[ organic light-emitting device ]
The present disclosure relates to an Organic Light Emitting Diode (OLED) in which a plurality of emission material layers each having a different level of delayed fluorescent material and an electron blocking layer having a controlled energy level compared to the delayed fluorescent material are applied, thereby reducing a driving voltage thereof and improving light emitting efficiency and light emitting life thereof, and an organic light emitting device having the same. The OLED is applicable to organic light emitting devices such as organic light emitting display devices and organic light emitting lighting devices. As an example, a display device to which the OLED is applied will be described.
Fig. 1 is a schematic cross-sectional view of an organic light emitting display device of the present disclosure. As shown in fig. 1, the organic light emitting display device 100 includes a substrate 110, a thin film transistor Tr on the substrate 110, and an Organic Light Emitting Diode (OLED) D connected to the thin film transistor Tr.
The substrate 110 may include, but is not limited to, glass, thin flexible materials, and/or polymer plastics. For example, the flexible material may be selected from the group consisting of Polyimide (PI), Polyethersulfone (PES), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), Polycarbonate (PC), and combinations thereof, but is not limited thereto. The substrate 110 on which the thin film transistor Tr and the OLED D are disposed forms an array substrate.
The buffer layer 122 may be disposed on the substrate 110, and the thin film transistor Tr is disposed on the buffer layer 122. The buffer layer 122 may be omitted.
The semiconductor layer 120 is disposed on the buffer layer 122. In one exemplary aspect, the semiconductor layer 120 may include, but is not limited to, an oxide semiconductor material. In this case, a light blocking pattern may be provided under the semiconductor layer 120, and the light blocking pattern may prevent light from being incident toward the semiconductor layer 120, thereby preventing the semiconductor layer 120 from being deteriorated by the light. Alternatively, the semiconductor layer 120 may include, but is not limited to, polysilicon. In this case, opposite edges of the semiconductor layer 120 may be doped with impurities.
A gate insulating layer 124 formed of an insulating material is disposed on the semiconductor layer 120. The gate insulating layer 124 may include, but is not limited to, an inorganic insulating material, such as silicon oxide (SiO)x) Or silicon nitride (SiN)x)。
A gate electrode 130 made of a conductive material such as metal is disposed on the gate insulating layer 124 so as to correspond to the center of the semiconductor layer 120. Although the gate insulating layer 124 is disposed on the entire region of the substrate 110 in fig. 1, the gate insulating layer 124 may be patterned identically to the gate electrode 130.
An interlayer insulating layer 132 formed of an insulating material is disposed on the gate electrode 130, covering the entire surface of the substrate 110. The interlayer insulating layer 132 may include, but is not limited to, an inorganic insulating material (e.g., silicon oxide (SiO))x) Or silicon nitride (SiN)x) Or an organic insulating material (e.g., benzocyclobutene or photo-acrylic).
The interlayer insulating layer 132 has first and second semiconductor layer contact holes 134 and 136 exposing both sides of the semiconductor layer 120. The first and second semiconductor layer contact holes 134 and 136 are disposed on both sides of the gate electrode 130, spaced apart from the gate electrode 130. In fig. 1, a first semiconductor layer contact hole 134 and a second semiconductor layer contact hole 136 are formed in the gate insulating layer 124. Alternatively, when the gate insulating layer 124 is identically patterned with the gate electrode 130, the first and second semiconductor layer contact holes 134 and 136 are formed only within the interlayer insulating layer 132.
A source electrode 144 and a drain electrode 146 made of a conductive material such as metal are disposed on the interlayer insulating layer 132. The source electrode 144 and the drain electrode 146 are spaced apart from each other with respect to the gate electrode 130 and contact both sides of the semiconductor layer 120 through the first semiconductor layer contact hole 134 and the second semiconductor layer contact hole 136, respectively.
The semiconductor layer 120, the gate electrode 130, the source electrode 144, and the drain electrode 146 constitute a thin film transistor Tr, which functions as a driving element. The thin film transistor Tr in fig. 1 has a coplanar structure in which a gate electrode 130, a source electrode 144, and a drain electrode 146 are disposed on the semiconductor layer 120. Alternatively, the thin film transistor Tr may have an inverted stack structure in which a gate electrode is disposed under a semiconductor layer and source and drain electrodes are disposed on the semiconductor layer. In this case, the semiconductor layer may include amorphous silicon.
The gate and data lines intersect each other to define a pixel region, and a switching element connected to the gate and data lines may be further formed in the pixel region of fig. 1. The switching element is connected to a thin film transistor Tr as a driving element. Further, the power line is spaced in parallel with the gate line or the data line, and the thin film transistor Tr may further include a storage capacitor configured to constantly maintain a voltage of the gate electrode during one frame.
In addition, the organic light emitting display device 100 may include a color filter containing a dye or pigment for transmitting light of a specific wavelength emitted from the OLED D. For example, a color filter may transmit light of a particular wavelength, such as red (R), green (G), blue (B), and/or white (W), for example. Each of red, green and blue color filters may be formed in each pixel region, respectively. In this case, the organic light emitting display device 100 may implement full color through a color filter.
For example, when the organic light emitting display apparatus 100 is a bottom emission type, a color filter may be disposed on the interlayer insulating layer 132 corresponding to the OLED D. Alternatively, when the organic light emitting display apparatus 100 is a top emission type, the color filter may be disposed over the OLED D (i.e., the second electrode 230).
A passivation layer 150 is disposed on the source and drain electrodes 144 and 146 on the entire substrate 110. The passivation layer 150 has a flat top surface and a drain electrode contact hole 152 exposing the drain electrode 146 of the thin film transistor Tr. Although the drain electrode contact hole 152 is disposed on the second semiconductor layer contact hole 136, it may be spaced apart from the second semiconductor layer contact hole 136.
The OLED D includes a first electrode 210 disposed on the passivation layer 150 and connected to the drain electrode 146 of the thin film transistor Tr. The OLED D further includes an emission layer 220 and a second electrode 230 each sequentially disposed on the first electrode 210.
The first electrode 210 is disposed in each pixel region. The first electrode 210 may be an anode and include a conductive material having a relatively high work function value. For example, the first electrode 210 may include, but is not limited to, a transparent conductive material such as Indium Tin Oxide (ITO), Indium Zinc Oxide (IZO), Indium Tin Zinc Oxide (ITZO), tin oxide (SnO), zinc oxide (ZnO), Indium Cerium Oxide (ICO), and aluminum-doped zinc oxide (AZO), etc.
In one exemplary aspect, when the organic light emitting display apparatus 100 is a top emission type, a reflective electrode or a reflective layer may be disposed under the first electrode 210. For example, the reflective electrode or reflective layer may include, but is not limited to, an aluminum-palladium-copper (APC) alloy. In addition, a bank layer 160 is disposed on the passivation layer 150 to cover an edge of the first electrode 210. The bank layer 160 exposes the center of the first electrode 210.
The emission layer 220 is disposed on the first electrode 210. In one exemplary aspect, the emission layer 220 may have a single-layer structure of an Emission Material Layer (EML). Alternatively, the emission layer 220 may have a multi-layer structure of a Hole Injection Layer (HIL), a Hole Transport Layer (HTL), an Electron Blocking Layer (EBL), an EML, a Hole Blocking Layer (HBL), an Electron Transport Layer (ETL), and/or an Electron Injection Layer (EIL) (see fig. 2). In one aspect, the emissive layer 220 may have one emissive unit. Alternatively, the emission layer 220 may have a plurality of emission units to form a series structure.
The second electrode 230 is disposed on the substrate 110 provided with the emission layer 220. The second electrode 230 may be disposed on the entire display area and may include a conductive material having a relatively low work function value compared to the first electrode 210. The second electrode 230 may be a cathode. For example, the second electrode 230 may include, but is not limited to, aluminum (Al), magnesium (Mg), calcium (Ca), silver (Ag), an alloy thereof, or a combination thereof, such as an aluminum-magnesium alloy (Al-Mg).
In addition, an encapsulation film 170 may be disposed on the second electrode 230 to prevent external moisture from penetrating into the OLED D. The encapsulation film 170 may have, but is not limited to, a stacked structure of a first inorganic insulating film 172, an organic insulating film 174, and a second inorganic insulating film 176.
In addition, a polarizer may be attached to the encapsulation film 170 to reduce external light reflection. For example, the polarizer may be a circular polarizer. In addition, the cover window may be attached to the encapsulation film 170 or the polarizer. In this case, the substrate 110 and the cover window may have flexibility, and thus the organic light emitting display device 100 may be a flexible display device.
[OLED]
We will now describe the OLED in more detail. Fig. 2 is a schematic cross-sectional view illustrating an OLED according to one exemplary aspect of the present disclosure. As shown in fig. 2, the OLED D includes a first electrode 210 and a second electrode 230 facing each other, and an emission layer 220 disposed between the first electrode 210 and the second electrode 230. In an exemplary aspect, the emissive layer 220 includes an EML 240 disposed between the first electrode 210 and the second electrode 230. In addition, the emission layer 220 further includes: an HIL 250, an HTL260, and an EBL 265 each sequentially disposed between the first electrode 210 and the EML 240; an ETL 270 and an EIL 280 each disposed between the EML 240 and the second electrode 230 in sequence; and optionally an HBL 275 disposed between the EML 240 and the ETL 270.
The first electrode 210 may be an anode that supplies holes to the EML 240. The first electrode 210 may include, but is not limited to, a conductive material having a relatively high work function value, for example, a Transparent Conductive Oxide (TCO). In one exemplary aspect, the first electrode 210 may include, but is not limited to, ITO, IZO, ITZO, SnO, ZnO, ICO, AZO, and the like.
The second electrode 230 may be a cathode that supplies electrons to the EML 240. The second electrode 230 may include, but is not limited to, a conductive material having a relatively low work function value, i.e., a highly reflective material, such as Al, Mg, Ca, Ag, alloys thereof, combinations thereof, and the like.
The EML 240 includes a first EML (EML1)242 disposed between the EBL 265 and the HBL, and a second EML (EML2)244 disposed between the EML 1242 and the HBL 275. EML 1242 and EML 244 each include a first compound and a second compound. The first compound may be a host and the second compound may be a delayed fluorescence material.
The first compounds in EML 1242 and EML 2244 may include, but are not limited to, 9- (3- (9H-carbazol-9-yl) phenyl) -9H-carbazole e-3-carbonitrile (mCP-CN), 4 '-bis (N-carbazolyl) -1,1' -biphenyl (CBP), 3 '-bis (N-carbazolyl) -1,1' -biphenyl (mCBP), 1, 3-bis (carbazol-9-yl) benzene (mCP), bis [2- (diphenylphosphino) phenyl ] ether oxide (DPEPO), 2, 8-bis (diphenylphosphoryl) dibenzothiophene (PPT), 1,3, 5-tris [ (3-pyridyl) -benzene-3-yl ] benzene (TmPyPB), 2, 6-bis (9H-carbazol-9-yl) pyridine (PYD-2Cz), 2, 8-bis (9H-carbazol-9-yl) dibenzothiophene (DCzDBT), 3', 5 ' -bis (carbazol-9-yl) - [1, 1' -biphenyl ] -3, 5-dicarbonitrile (DCzTPA), 4' - (9H-carbazol-9-yl) biphenyl-3, 5-dicarbonitrile (pCzB-2CN), 3' - (9H-carbazol-9-yl) biphenyl-3, 5-dicarbonitrile (mCZB-2CN), diphenyl-4-triphenylsilylphenyl-phosphine oxide (TSPO1), 9- (9-phenyl-9H-carbazol-6-yl) -9H-carbazole (CCP), 4- (3- (triphenylen-2-yl) phenyl) dibenzo [ b, d ] thiophene, 9- (4- (9H-carbazol-9-yl) phenyl) -9H-3,9 ' -bicarbazole, 9- (3- (9H-carbazol-9-yl) phenyl) -9H-3,9 ' -bicarbazole and/or 9- (6- (9H-carbazol-9-yl) pyridin-3-yl) -9H-3,9 ' -bicarbazole).
EML 1242 and EML 2244 each include a second compound as a delayed fluorescent material. When holes and electrons are satisfied to form excitons, singlet excitons of a paired spin state and triplet excitons of an unpaired spin state are theoretically generated at a ratio of 1: 3. Since conventional fluorescent materials can utilize only singlet excitons, they exhibit low luminous efficiency. Phosphorescent materials can utilize triplet excitons as well as singlet excitons, but they exhibit excessively short emission lifetimes and are not suitable for use in commercial devices.
Delayed fluorescence materials such as Thermally Activated Delayed Fluorescence (TADF) have been developed, which can solve the fluorescent and/or phosphorescent materials of the conventional artWith attendant problems. Excited singlet level S of delayed fluorescence material DF1 DFAnd excited triplet energy level T1 DFEnergy band gap Δ E betweenST DFVery narrow (see fig. 3). Thus, the singlet level S in the delayed-fluorescence material DF1 DFExciton and triplet energy level T1 DFMay be transferred to an intermediate energy level state, i.e., ICT state, and then the intermediate state exciton may be transferred to a ground state (S)0 DF；S1 DF→ICT←T1 DF)。
Since the delayed fluorescence material DF has an electron acceptor moiety spaced apart from an electron donor moiety within the molecule, it exists in a polarized state having a large dipole moment within the molecule. Since there is little interaction between HOMO and LUMO in the state of dipole moment polarization, triplet excitons as well as singlet excitons may be converted to ICT states.
Excited singlet level S of delayed fluorescence material DF1 DFAnd excited triplet energy level T1 DFEnergy band gap Δ E betweenST DFMust be equal to or less than about 0.3eV, such as from about 0.05eV to about 0.3eV, such that the singlet level S is excited1 DFAnd excited triplet energy level T1 DThe exciton energy in (b) can transition to the ICT state. Singlet energy level S1 DFAnd triplet energy level T1 DFEnergy band gap Δ E betweenST DFSmall materials may exhibit ordinary fluorescence (with singlet level S) using intersystem crossing (ISC)1 DFCan be transited to the triplet energy level T1 DFExcitons of (b) and delayed fluorescence (in which the triplet level T is the triplet level) by reverse intersystem crossing (RISC)1 DFThe exciton can be transited upwards to the singlet state energy level S1 DFThen from the triplet energy level T1 DFSinglet energy level S of transition1 DFThe exciton of (a) may transition to the ground state S0 DF). In other words, the energy level S of the delayed fluorescence material DF at the excited singlet state1 DFAnd at excited triplet energy level T 1 DF75% of the excitons may be converted into the ICT state, and then the converted excitons drop to the ground state S with emission of light0. Therefore, the delayed fluorescent material can theoretically have an internal quantum efficiency of 100%.
In one exemplary aspect, the second compound as the delayed fluorescence material DF in the EML 1242 and EML 2244 may be a carbazole-based delayed fluorescence material. The carbazole-based delayed fluorescent material may have a structure of the following chemical formula 1:
[ chemical formula 1]
Figure BDA0002692335410000101
In chemical formula 1, R1And R2Each independently is hydrogen or C1-C20An alkyl group; and n is an integer of 0 to 4.
As used herein, the term "without substituents" means attached to hydrogen, in which case hydrogen includes protium, deuterium, and tritium.
As used herein, a substituent in the term "having a substituent" includes, but is not limited to, C having no substituent or halogen substitution1-C20Alkyl, unsubstituted or halogen-substituted C1-C20Alkoxy, halogen, cyano, -CF3Hydroxyl, carboxyl, carbonyl, amino, C1-C10Alkylamino radical, C6-C30Arylamino, C3-C30Heteroarylamino group, C6-C30Aryl radical, C3-C30Heteroaryl, nitro, hydrazide, sulfonate, C1-C20Alkylsilyl group, C6-C30Arylsilyl and C3-C30A heteroaryl silyl group.
As used herein, the term "hetero", such as in "heteroaryl ring", "heteroarylene", "heteroarylalkylene", "heteroaryloxylene", "heterocycloalkyl", "heteroaryl", "heteroarylalkyl", "heteroaryloxy", "heteroarylamino", means that at least one carbon atom (e.g., 1 to 5 carbon atoms) constituting an aromatic or aliphatic ring is substituted with at least one heteroatom selected from the group consisting of N, O, S, P and combinations thereof.
For example, the carbazole-based delayed fluorescence material may include any one having the structure of the following chemical formula 2:
[ chemical formula 2]
Figure BDA0002692335410000102
Figure BDA0002692335410000111
In another exemplary aspect, the second compound as the delayed fluorescent material DF in the EML 1242 and EML 2244 may be a triazine-based delayed fluorescent material. The triazine-based delayed fluorescent material may have a structure of the following chemical formula 3:
[ chemical formula 3]
Figure BDA0002692335410000121
In chemical formula 3, R11And R12Each independently is hydrogen or C1-C20An alkyl group; r13Is unsubstituted or substituted C8-C30Condensed heteroaryl, unsubstituted or substituted C6-C20Aromatic amino group or unsubstituted or substituted C3-C20A heteroaromatic amino group, wherein the fused heteroaryl group includes at least one of a carbazolyl moiety, an acridinyl moiety, a phenazinyl moiety, and a phenoxazinyl moiety.
As an example, C8-C30Condensed heteroaryl, C6-C20Arylamino and C3-C20Each heteroarylamino group may be unsubstituted or substituted by C1-C10Alkyl radical, C6-C30Aryl and C3-C30At least one group of heteroaryl. As used herein, C6-C30The aryl group may include C6-C30Aryl radical, C7-C30Aralkyl radical, C6-C30Aryloxy radical and C6-C30An arylamino group. As used herein, C3-C30Heteroaryl may include C3-C30Heteroaryl group, C4-C30Heteroaralkyl radical, C3-C30Heteroaryloxy and C3-C30A heteroarylamino group.
As an example, a fused heteroaryl group can include a carbazolyl moiety, an acridinyl moiety, a phenazinyl moiety, and a phenoxazinyl moiety. In addition, the fused heteroaryl group may further include an aromatic ring or a heteroaromatic ring fused with these moieties, for example, a benzene ring, a naphthalene ring, an indene ring, a pyridine ring, an indole ring, a furan ring, a benzofuran ring, a dibenzofuran ring, a thiophene ring, a benzothiophene ring, and/or a dibenzothiophene ring. For example, the fused heteroaryl group can include unsubstituted or substituted indolocarbazolyl moieties, unsubstituted or substituted benzothienocarbazolyl moieties. For example, the triazine-based delayed fluorescent material having the structure of chemical formula 3 may include any one of the structures having the following chemical formula 4:
[ chemical formula 4]
Figure BDA0002692335410000131
Figure BDA0002692335410000141
In one exemplary aspect, the level of second compound DF in EML 1242 disposed adjacent to EBL 265 may be lower than the level of second compound DF in EML 2244 disposed adjacent to HBL 275.
As an example, the triazine-based delayed fluorescent material having the structures of chemical formulas 3 and 4 has relatively high electron transport characteristics compared to hole transport characteristics. When the level of the second compound DF in the EML 1242 is higher than or equal to the level of the second compound DF in the EML 2244, electrons are injected into the EML 1242 faster than holes. In this case, a recombination region between holes and electrons is formed at the interface of the EBL 264 and the EML 1242, which allows an increase in driving voltage in the OLED D, but does not improve light emission efficiency and light emission lifetime thereof.
In an exemplary aspect, the content of the second compound DF in the EML 1242 may be about 5 wt% to about 30 wt%, and the content of the second compound DF in the EML 2244 may be about 40 wt% to about 50 wt%, but the disclosure is not limited thereto. When the content of the second compound DF in the EML 1242 exceeds about 30 wt% and/or the content of the second compound DF in the EML 2244 exceeds about 50 wt%, electrons are trapped in the EML 2244 and excitons are not efficiently generated.
In another exemplary aspect, the thickness of EML 1242 may be thinner than the thickness of EML 2244. For example, the thickness of EML 1242 may be, but is not limited to, about 3nm to about 10nm (e.g., about 3nm to about 5nm), and the thickness of EML 2244 may be, but is not limited to, about 20nm to about 50nm (e.g., about 30nm to about 50 nm). By adjusting the thicknesses of EML 1242 and EML 2244, each containing a different level of the second compound DF, it is possible to induce a recombination region between holes and electrons to form at the central region of EML 240 (e.g., at EML 2244).
As described above, as a conventional phosphorescent material containing a heavy metal, a delayed fluorescent material can theoretically realize an internal quantum efficiency of 100% at maximum. The host for achieving delayed fluorescence should induce triplet excitons on the dopant to participate in the luminescence process without quenching or non-radiative recombination. For this purpose, the energy level between the host and the delayed fluorescent material should be adjusted.
Fig. 3 is a schematic diagram illustrating a light emitting mechanism through an energy band gap between light emitting materials according to the present disclosure. As shown in FIG. 3, the excited singlet level S of the first compound, which can be the host in EML 2401 HAnd excited triplet energy level T1 HRespectively higher than excited singlet level S of a second compound DF having delayed fluorescence1 DFAnd excited triplet energy level T1 DF. As an example, the excited triplet level T of the first compound H1 HCan be higher than the excited triplet energy level T of the second compound DF1 DFAt least about 0.2eV, preferably at least about 0.3eV, and more preferably at least about 0.5 eV.
When excited triplet energy level T of the first compound1 HAnd/or excited singlet energy level S1 HNot sufficiently higher than the excited triplet level T of the second compound DF1 DFAnd/or excited singlet energy level S1 DFWhen the triplet exciton energy of the second compound DF may be reversely transferred to the excited triplet level T of the first compound1 H. In this case, triplet excitons that are reversely transferred to the first compound incapable of emitting triplet excitons are quenched without being discharged, so that triplet exciton energy of the second compound DF having a delayed fluorescence characteristic cannot contribute to light emission. As an example, the excited singlet level S of the second compound DF having delayed fluorescence Property1 DFAnd excited triplet energy level T1 DFEnergy band gap Δ E betweenST DFMay be equal to or less than about 0.3eV, such as from about 0.05eV to about 0.3 eV.
In addition, it is preferable that the HOMO level (HOMO) of the first compoundH) With the HOMO energy level (HOMO) of the second compoundDF) Energy level band gap (| HOMO)H-HOMODFI) or the LUMO energy Level (LUMO) of the first compoundH) With the LUMO energy Level (LUMO) of the second compoundDF) Bandgap of energy level (| LUMO)H-LUMODFL) may be equal to or less than about 0.5eV, for example from about 0.1eV to about 0.5eV (see fig. 6). In this case, charges can be efficiently transported from the first compound as a host to the second compound as a delayed fluorescent material, thereby improving the final light emitting efficiency in the EML 240.
Returning to fig. 2, the HIL 250 is disposed between the first electrode 210 and the HTL260, and improves the interface characteristics between the inorganic first electrode 210 and the organic HTL 260. In one exemplary aspect, HIL 340 can include, but is not limited to, 4', 4 ″ -tris (3-methylphenylamino) triphenylamine (MTDATA), 4', 4 ″ -tris (N, N-diphenyl-amino) triphenylamine (NATA), 4', 4 ″ -tris (N- (naphthalen-1-yl) -N-phenyl-amino) triphenylamine (1T-NATA), 4', 4 ″ -tris (N- (naphthalen-2-yl) -N-phenyl-amino) triphenylamine (2T-NATA), copper phthalocyanine (CuPc), tris (4-carbazol-9-yl-phenyl) amine (TCTA), N '-diphenyl-N, N' -bis (1-naphthyl) -1,1 '-Biphenyl-4, 4' -diamine (NPB; NPD), 1,4,5,8,9, 11-hexaazatriphenylene-hexacyano-nitrile (bipyrazine [2,3-f:2'3' -H ] quinoxaline-2, 3,6,7,10, 11-hexacyano-nitrile; HAT-CN), 1,3, 5-tris [4- (diphenylamino) phenyl ] benzene (TDAPB), poly (3, 4-ethylenedioxythiophene) polystyrenesulphonic acid (PEDOT/PSS) and/or N- (Biphenyl-4-yl) -9, 9-dimethyl-N- (4- (9-phenyl-9H-carbazol-3-yl) phenyl) -9H-fluoren-2-amine. The HIL 250 may be omitted according to the structure of the OLED D.
The HTL260 is disposed adjacent to the EML 240 between the first electrode 210 and the EML 240. In one exemplary aspect, the HTL260 may include, but is not limited to, N ' -diphenyl-N, N ' -bis (3-methylphenyl) -1,1' -biphenyl-4, 4' -diamine (TPD), NPB, 4' -bis (N-carbazolyl) -1,1' -biphenyl (CBP), poly [ N, N ' -bis (4-butylphenyl) -N, N ' -bis (phenyl) -benzidine ] (poly-TPD), copoly [ (9, 9-dioctylfluorenyl-2, 7-diyl) - (4,4' - (N- (4-sec-butylphenyl) diphenylamine)) (TFB), bis [4- (N, N-di-p-tolyl-amino) -phenyl ] cyclohexane (TAPC) ] (TFB), 3, 5-bis (9H-carbazol-9-yl) -N, N-diphenylamine (DCDPA), N- (biphenyl-4-yl) -9, 9-dimethyl-N- (4- (9-phenyl-9H-carbazol-3-yl) phenyl) -9H-fluoren-2-amine and/or N- (biphenyl-4-yl) -N- (4- (9-phenyl-9H-carbazol-3-yl) phenyl) biphenyl-4-amine.
An ETL 270 and an EIL 280 may be sequentially disposed between the EML 240 and the second electrode 230. The ETL 270 includes a material having high electron mobility to stably supply electrons to the EML 240 through fast electron transport. In one exemplary aspect, the ETL 270 may include, but is not limited to, oxadiazole compounds, triazole compounds, phenanthroline compounds, benzoxazole compounds, benzothiazole compounds, benzimidazole compounds, triazine compounds, and the like.
By way of example, the ETL 270 may include, but is not limited to: tris-8-hydroxyquinoline aluminium (Alq)3) 2-biphenyl-4-yl-5- (4-tert-butylphenyl) -1,3,4Oxadiazole (PBD), spiro-PBD, lithium quinoline (Liq), 1,3, 5-tris (N-phenylbenzimidazol-2-yl) benzene (TPBi), bis (2-methyl-8-hydroxyquinoline-N1, O8) - (1,1' -biphenyl-4-hydroxy) aluminum (BALq), 4, 7-diphenyl-1, 10-phenanthroline (Bphen), 2, 9-bis (naphthalen-2-yl) -4, 7-diphenyl-1, 10-phenanthroline (NBphen), 2, 9-dimethyl-4, 7-diphenyl-1, 10-phenanthroline (BCP), 3- (4-biphenyl) -4-phenyl-5-tert-butylphenyl-1, 2, 4-Triazole (TAZ), 4- (naphthalen-1-yl) -3, 5-diphenyl-4H-1, 2, 4-triazole (NTAZ), 1,3, 5-tris (p-pyridin-3-yl-phenyl) benzene (TpPyPB), 2,4, 6-tris (3'- (pyridin-3-yl) biphenyl-3-yl) 1,3, 5-triazine (TmPPPyTz), poly [9, 9-bis (3' - ((N, N-dimethyl) -N-ethylammonium) -propyl) -2, 7-fluorene]-Cross-2, 7- (9, 9-dioctylfluorene)](PFNBr), tris (phenylquinoxaline) (TPQ) and/or TSPO 1.
The EIL 280 is disposed between the second electrode 230 and the ETL 270, and may improve physical characteristics of the second electrode 230, and thus may improve the lifespan of the OLED D. In an exemplary aspect, the EIL 280 can include, but is not limited to, alkali metal halides (e.g., LiF, CsF, NaF, and BaF)2Etc.) and/or organometallic compounds (e.g., lithium quinolinate, lithium benzoate, sodium stearate, etc.).
When holes are transferred to the second electrode 230 via the EML 240 and/or electrons are transferred to the first electrode 210 via the EML 240, the OLED D may have a short lifetime and a reduced light emitting efficiency. To prevent these phenomena, the OLED D of the present invention includes an EBL 265 disposed between the HTL260 and the EML 240.
In addition, the OLED D may further include the HBL 275 as a second exciton blocking layer between the EML 240 and the ETL 270, so that holes cannot be transferred from the EML 240 to the ETL 270. In one exemplary aspect, HBL 275 may include, but is not limited to, oxadiazole compounds, triazole compounds, phenanthroline compounds, benzoxazole compounds, benzothiazole compounds, benzimidazole compounds, and triazine compounds, all of which may be used in ETL 270.
For example, HBL 275 may include compounds that have relatively low HOMO levels compared to the light emitting material in EML 240. HBL 275 may include, but is not limited to, mCBP, BCP, BALq, Alq3PBD, spiro-PBD, Liq, bis-4, 5- (3, 5-bis-3-pyridylphenyl) -2-methylpyrimidine (B3PYMPM), DPEPO, TSPO1, and combinations thereof.
As described above, EBL 264 is disposed between HTL260 and EML 240. As an example, the HOMO (highest occupied molecular orbital) energy level HOMO of the second compound DF in EML 1242 and EML 2244DFHOMO energy level HOMO with EBL 265EBLThe following relationship in the formula (1) can be satisfied:
0eV<HOMOEBL–HOMODF<0.4eV (1)
when the HOMO level between the EBL 265 and the second delayed fluorescent material DF satisfies the relationship in formula (1), holes can be efficiently transported and injected from the EBL 265 into the EML 240, and a recombination region between the holes and electrons can be formed in the central region in the EML 240. As an example, the HOMO level HOMO of the second compound DF in the EML 240DFHOMO energy level HOMO of ratio EBL 265EBLAs low as about 0.3 eV.
In one exemplary aspect, EBL 260 can include an organic compound having a (hetero) aromatic amino group. Such an organic compound having a (hetero) aromatic amino group may have the structure of the following chemical formula 5:
[ chemical formula 5]
Figure BDA0002692335410000171
In chemical formula 5, wherein R21To R23Each independently is unsubstituted or substituted C6-C30Aryl or unsubstituted or substituted C3-C20A heteroaromatic amino group.
As an example, R21To R23C in (1)6-C30Aryl or C3-C20The heteroaromatic amino groups may each have no substituent or be substituted by a group selected from C1-C10Alkyl radical, C6-C30Aryl and C3-C30At least one group of heteroaryl. More specifically, the (hetero) aromatic amino group-containing organic compound of chemical formula 5 may include any organic compound having the structure of chemical formula 6 below:
[ chemical formula 6]
Figure BDA0002692335410000181
Figure BDA0002692335410000191
In another exemplary aspect, EBL 265 may include carbazole-based organic compounds. The carbazole-based organic compound in EBL 265 may have the structure of the following chemical formula 7:
[ chemical formula 7]
Figure BDA0002692335410000192
In chemical formula 7, R31Is unsubstituted or substituted C6-C20An aryl group; r32And R33Each independently is hydrogen or a substituted or unsubstituted carbazolyl group, wherein R is32And R33Is a carbazolyl group; r34And R35Each independently hydrogen, unsubstituted or substituted C1-C10Alkyl, unsubstituted or substituted C6-C20Aryl or unsubstituted or substituted C3-C20A heteroaryl group; and p and q are each an integer of 0 or 1.
As an example, R32The carbazolyl group in (1) may be unsubstituted or substituted by C1-C10Alkyl radical, C6-C30Aryl and C3-C30At least one group of heteroaryl. More specifically, the carbazole-based organic compound in EBL 265 of chemical formula 7 may include any organic compound having a structure of the following chemical formula 8:
[ chemical formula 8]
Figure BDA0002692335410000201
As described above, the HOMO level HOMO of the second compound DF as the delayed fluorescent material in the EML 1242 and EML 2244DFHOMO energy level HOMO with EBL 265EBLThe relationship in the formula (1) should be satisfied. When these HOMO energy level relationships are not satisfied, charge transport or charge trapping problems may occur.
Fig. 4 is a schematic diagram showing a charge transport problem caused by the HOMO level band gap between the EML and the EBL in one comparative example, in which EML 240 includes carbazole-based delayed fluorescent materials having the structures of chemical formulas 1 and 2 as the second compound DF, and EBL 265 includes (hetero) aromatic amino-based compounds having the structures of chemical formulas 5 and 6.
As shown in FIG. 4, the LUMO (lowest unoccupied molecular orbital) energy level LUMO of EBL 265EBLThe LUMO energy level LUMO of the first compound H and the second compound DF in EML 240HAnd LUMODFShallow, electrons can therefore be effectively blocked at EBL 265. On the other hand, when the EML 240 includes carbazole-based delayed phosphors having structures of chemical formulas 1 and 2 as the delayed phosphor (second compound DF) and the EBL 265 includes (hetero) aromatic amino-based compounds having structures of chemical formulas 5 and 6, the HOMO level HOMO of the EBL 265 is the HOMO level HOMOEBLHOMO energy level HOMO with the second compound DF as delayed fluorescent material in EML 240DFThe energy level bandgap Δ HOMO1 in between is very large, i.e., greater than or equal to about 0.4 eV. In this case, holes are not transferred from EBL 265 to the first compound H as a host and the second compound DF as a delayed fluorescent material in EML 240 as positively charged carriers, but holes are accumulated at the interface between EBL 265 and EML 240. As holes accumulate at the interface between EBL 265 and EML 240, the driving voltage of OLED D increases. When the holes are quenched without emission without forming excitons and participating in the light emitting process, the light emitting efficiency and the light emitting lifetime of the OLED D are reduced.
FIG. 5 is a schematic diagram showing a charge trap problem caused by a HOMO level bandgap between an EML and an EBL in another comparative example, in which an EML 240 contains a compound having a chemical formula as a second compound3 and 4, and EBL 265 includes carbazole-based organic compounds having structures of chemical formulas 7 and 8. In this case, the HOMO level HOMO of the second compound DF as the delayed fluorescent material in the EML 240DFHOMO energy level HOMO of carbazole-based organic compound in EBL 265EBLShallow. Holes are directly transferred from EBL 265 to the second compound DF as a delayed fluorescent material without passing through the first compound DF as a host in the EML 240, and thus, holes are trapped at the second compound DF. As the hole trapped at the second compound DF and the electron trapped at the first compound H form an excited complex, the driving voltage of the OLED D increases while the light emission life of the OLED D deteriorates.
Fig. 6 is a schematic diagram illustrating injection of charges without any charge transport problem or charge trap problem by controlling the HOMO level band gap between the EML and the EBL in the present disclosure, wherein the EML 240 includes carbazole-based delayed fluorescent materials having structures of chemical formulas 1 and 2 as the second compound DF, and the EBL 265 includes carbazole-based organic compounds having structures of chemical formulas 7 and 8; or the EML 240 includes triazine-based delayed fluorescent materials having structures of chemical formulas 3 and 4 as the second compound DF, and the EBL 265 includes (hetero) aromatic amino-based organic compounds having structures of chemical formulas 5 and 6.
In this case, the HOMO level HOMO of the second compound DF as the delayed fluorescent material in the EML 240DFHOMO energy level HOMO with EBL 265EBLThe energy level band gap Δ HOMO2 therebetween can satisfy the relationship in formula (1). Holes can be rapidly transferred from EBL 265 via first compound H in EML 240 and injected into second compound DF. Since the driving voltage of the OLED D is reduced and the recombination region between the holes and the electrons moves to the central region of the EML 240, the reduction of the light emitting efficiency and the light emitting life of the OLED D due to the exciton loss may be minimized.
Example 1 (ex.1): fabrication of OLEDs
An OLED was manufactured in which the compound 3-4(LUMO-2.2 eV; HOMO-5.5eV) in chemical formula 5 was applied to EBL and mCBP (LUMO-2.5 eV; HOMO-6.0eV) and a compound 2-2(LUMO: -3.0 eV; HOMO: -5.6eV) was applied to EML1 and EML 2. The ITO (50nm) attached glass substrate was washed with ozone and loaded in a vacuum system and then transferred to a vacuum deposition chamber for deposition of other layers on the substrate. At 10-7Under support and set the deposition rate to
Figure BDA0002692335410000221
The organic layers were deposited by evaporation from a heated boat in the following order:
ITO (50 nm); HIL (HAT-CN; 10 nm); HTL (NPB,75 nm); EBL (Compound 3-4,15 nm); EML1(mCBP (80 wt%): compound 2-2(20 wt%), 5 nm); EML2(mCBP (60 wt%): compound 2-2(40 wt%), 40 nm); HBL (B3PYMPM,10 nm); ETL (TPBi,25 nm); eil (lif); and a cathode (Al).
Then, a capping layer (CPL) was deposited on the cathode and the device was encapsulated with glass. After the deposition of the emission layer and the cathode, the OLED was transferred from the deposition chamber to a dry box for film formation, and then encapsulated with an ultraviolet curable epoxy resin and a moisture absorbent.
Example 2 (ex.2): fabrication of OLEDs
An OLED was manufactured using the same material as example 1, except that compound 4-1(LUMO-2.3 eV; HOMO-5.7eV) in chemical formula 8 in the EBL was used instead of compound 3-4, and compound 1-23(LUMO-3.4 eV; HOMO-5.9eV) in chemical formula 2 as a delayed fluorescence material in EML1 and EML2 was used instead of compound 2-2, and the concentration of compound 1-23 in EML1 was changed to 5 wt%.
Examples 3 to 8 (ex.3-ex.8): fabrication of OLEDs
An OLED was manufactured using the same material as example 2, except that the concentration of the compounds 1 to 23 as the delayed fluorescence material in the EML1 was changed to 10 wt% (ex.3), 15 wt% (ex.4), 20 wt% (ex.5), 25 wt% (ex.6), 30 wt% (ex.7), or 35 wt% (ex.8).
Example 9 (ex.9): fabrication of OLEDs
An OLED was fabricated using the same materials as in example 1, except that compound 3-4 was replaced with compound 3-1(LUMO-2.3 eV; HOMO-5.5eV) in chemical formula 6 in the EBL.
Example 10 (ex.10): fabrication of OLEDs
An OLED was fabricated using the same materials as in example 5, except that compound 4-1 was replaced with compound 4-12(LUMO-2.2 eV; HOMO-5.7eV) in chemical formula 8 in EBL.
Comparative example 1 (ref.1): fabrication of OLEDs
An OLED was fabricated using the same materials as in example 1, except that compounds 3-4(LUMO-2.2 eV; HOMO-5.5eV) in the EBL were used in place of compounds 3-4, and that single EML (mCBP (host, 60 wt%)) was used in place of dual EML, compounds 1-23 (delayed fluorescence material, 40 wt%; LUMO-3.4 eV; HOMO-5.9eV), 40 nm.
Comparative example 2 (ref.2): fabrication of OLEDs
An OLED was fabricated using the same materials as in comparative example 1, except that compound 2-2(LUMO-3.0 eV; HOMO-5.6eV), which is a delayed fluorescence material in a single EML, was used in place of compound 1-23.
Comparative example 3 (ref.3): fabrication of OLEDs
An OLED was fabricated using the same materials as in comparative example 1, except that compound 4-1(LUMO-2.3 eV; HOMO-5.7eV) in the EBL was used in place of compound 3-4.
Comparative example 4 (ref.4): fabrication of OLEDs
An OLED was manufactured using the same material as comparative example 3, except that compound 2-2 as a delayed fluorescence material in the single EML was used instead of compound 1-23.
Comparative example 5 (ref.5): fabrication of OLEDs
An OLED was fabricated using the same materials as in example 1, except that compounds 1-23(LUMO-3.4 eV; HOMO-5.9eV) as delayed fluorescence materials in EML1 and EML2 were used in place of compound 2-2.
Comparative examples 6 to 9 (Ref.6-Ref.9): fabrication of OLEDs
An OLED was manufactured using the same material as example 2, except that the concentration of compounds 1 to 23 as a delayed fluorescence material in EML1 was changed to 5 wt% (ref.6), 50 wt% (ref.7), 60 wt% (ref.8), or 70 wt% (ref.9).
Comparative example 10 (ref.10): fabrication of OLEDs
An OLED was fabricated using the same materials as in example 1, except that compound 4-1(LUMO-2.3 eV; HOMO-5.7eV) in the EBL was used in place of compound 3-4.
Comparative example 11 (ref.11): fabrication of OLEDs
An OLED was manufactured using the same material as comparative example 2, except that the concentration of compounds 1 to 23 in EML1(40nm) was changed to 40 wt%, and the concentration of compounds 1 to 23 in EML2(5nm) was changed to 10 wt%.
Comparative example 12 (ref.12): fabrication of OLEDs
An OLED was manufactured using the same material as comparative example 11, except that the concentration of compounds 1 to 23 in EML2 was changed to 70 wt%.
Comparative example 13 (ref.13): fabrication of OLEDs
An OLED was manufactured using the same material as example 2, except that three EMLs, namely EML1(mCBP as a host (80 wt%): compounds 1 to 23 as a delayed fluorescence material (20 wt%), 13nm), EML2(mCBP (70 wt%): compounds 1 to 23(30 wt%), 13nm) and EML3(mCBP (60 wt%): compounds 1 to 23(40 wt%), 13nm) were used instead of the two EMLs.
Comparative example 14 (ref.14): fabrication of OLEDs
OLEDs were manufactured using the same materials as in comparative example 13, except that the concentrations of the compounds 1 to 23 in each of the EML1, EML2, and EML3 were changed to 40 wt%, 30 wt%, and 20 wt%, respectively.
Experimental example:measurement of light emission properties of OLED
Each of the OLEDs manufactured according to examples 1 to 10 and comparative examples 1 to 15 was connected to an external power source, and then the light emitting properties of all the diodes were evaluated at room temperature using a constant current source (KEITHLEY) and a photometer PR 650. In particular 6.3mA/m2Drive voltage (V) at current density, current efficiency (cd/A), power efficiency (lm/W), maximum electroluminescence wavelength (EL lambda)maxNm), external quantum efficiency (EQE,%), and T95(duration of 95% brightness from initial brightness, hour). The results are shown in tables 1 and 2 below.
Table 1: luminescent properties of OLEDs
Figure BDA0002692335410000241
Figure BDA0002692335410000251
Table 2: luminescent properties of OLEDs
Figure BDA0002692335410000252
As shown in tables 1 and 2, the driving voltage of the OLEDs in examples 1 to 10 was reduced by at most 27.3% and the current efficiency, power efficiency, EQE and emission lifetime (T) thereof were reduced as compared to the OLEDs of comparative examples 1 to 4 in which a single EML had a high concentration (40 wt%) of the delayed fluorescent material95) Increases by at most 38.8%, 27.6%, 29.0% and 407.1%, respectively. In addition, the driving voltage of the OLEDs in examples 1 to 10 was reduced by at most 25.6% and the current efficiency, power efficiency, EQE, and emission lifetime (T) thereof were reduced as compared to the OLEDs in comparative examples 5 and 10 in which the HOMO level between the EBL and the delayed fluorescent material was not controlled95) Increases by at most 43.6%, 38.2%, 33.6% and 317.6%, respectively. In addition, the EML1 had a high concentration (4) as compared with those in comparative examples 6 to 9 and comparative examples 11 to 120 wt% or more) of the delayed fluorescence material, the driving voltage of the OLED in examples 1 to 10 was reduced by up to 30.4%, and the current efficiency, power efficiency, EQE and emission lifetime (T) thereof were reduced by up to 30.4%95) Increases of at most 78.0%, 103.0%, 67.8% and 273.7%, respectively. In addition, the driving voltage of the OLEDs in examples 1 to 10 was reduced by up to 28.9% as compared to the OLEDs of comparative examples 13 to 14 in which the three EMLs have different delayed fluorescent materials with gradually increasing thickness and concentration, and the current efficiency, power efficiency, EQE, and emission lifetime (T) thereof95) Increases of up to 109.8%, 117.5%, 31.0% and 208.7%, respectively.
It will be apparent to those skilled in the art that various modifications and variations can be made in the Organic Light Emitting Diode (OLED) and the organic light emitting device including the OLED of the present disclosure without departing from the technical concept or scope of the present disclosure. Thus, it is intended that the present disclosure cover the modifications and variations of this disclosure provided they come within the scope of the appended claims and their equivalents.

Claims (20)

1. An organic light emitting diode, comprising:
a first electrode;
a second electrode facing the first electrode;
a first emissive material layer disposed between the first electrode and the second electrode;
a second emissive material layer disposed between the first emissive material layer and the second electrode; and
an electron blocking layer disposed between the first electrode and the first emissive material layer,
wherein the first emissive material layer and the second emissive material layer each comprise a first compound and a second compound,
wherein the second compound includes an organic compound having a structure of the following chemical formula 1 or chemical formula 3,
wherein a level of the second compound in the first emissive material layer is higher than a level of the second compound in the second emissive material layer, and
wherein the HOMO (highest occupied molecular orbital) energy level of the second compoundDFAnd the HOMO energy level HOMO of the electron blocking layerEBLSatisfies the relationship in the following formula (1):
0eV<HOMOEBL–HOMODF<0.4eV (1)；
[ chemical formula 1]
Figure FDA0002692335400000011
Wherein R is1And R2Each independently is hydrogen or C1-C20An alkyl group; and n is an integer from 0 to 4;
[ chemical formula 3]
Figure FDA0002692335400000021
Wherein R is11And R12Each independently is hydrogen or C1-C20An alkyl group; and R is13Is unsubstituted or substituted C8-C30Condensed heteroaryl, unsubstituted or substituted C6-C20Aromatic amino group, or unsubstituted or substituted C3-C20A heteroaromatic amino group, wherein the fused heteroaryl group comprises at least one of a carbazolyl moiety, an acridinyl moiety, a phenazinyl moiety, and a phenoxazinyl moiety.
2. The organic light emitting diode of claim 1, wherein the second compound comprises the organic compound having the structure of chemical formula 1, and wherein the electron blocking layer comprises an organic compound having a structure of chemical formula 5 below:
[ chemical formula 5]
Figure FDA0002692335400000022
Wherein R is21To R23Each independently is unsubstituted or substituted C6-C30Aryl or unsubstituted or substituted C3-C20A heteroaromatic amino group.
3. The organic light emitting diode of claim 1, wherein the second compound comprises the organic compound having the structure of chemical formula 3, and wherein the electron blocking layer comprises an organic compound having a structure of chemical formula 7 below:
[ chemical formula 7]
Figure FDA0002692335400000031
Wherein R is31Is unsubstituted or substituted C6-C20An aryl group; r32And R33Each independently is hydrogen or a substituted or unsubstituted carbazolyl group, wherein R is32And R33Is a carbazolyl group; r34And R35Each independently hydrogen, unsubstituted or substituted C1-C10Alkyl, unsubstituted or substituted C6-C20Aryl or unsubstituted or substituted C3-C20A heteroaryl group; and p and q are each an integer of 0 or 1.
4. The organic light emitting diode of claim 1, wherein the second compound is present in the first emissive material layer in an amount from about 5 wt% to about 35 wt%, and the second compound is present in the second emissive material layer in an amount from about 40 wt% to about 50 wt%.
5. The organic light emitting diode of claim 1, wherein a thickness of the first emitting material layer is thinner than a thickness of the second emitting material layer.
6. The organic light emitting diode of claim 1, wherein the organic compound having the structure of chemical formula 1 includes any one selected from the group consisting of:
Figure FDA0002692335400000032
Figure FDA0002692335400000041
7. the organic light emitting diode of claim 1, wherein the organic compound having the structure of chemical formula 3 includes any one selected from the group consisting of:
Figure FDA0002692335400000051
Figure FDA0002692335400000061
8. the organic light emitting diode of claim 2, wherein the organic compound having the structure of chemical formula 5 includes any one selected from the group consisting of:
Figure FDA0002692335400000062
Figure FDA0002692335400000071
9. the organic light emitting diode of claim 3, wherein the organic compound having the structure of chemical formula 7 includes any one selected from the group consisting of:
Figure FDA0002692335400000072
Figure FDA0002692335400000081
10. the organic light emitting diode of claim 1, wherein the excited singlet energy level of the first compound is higher than the excited singlet energy level of the second compound, and the excited triplet energy level of the first compound is higher than the excited triplet energy level of the second compound.
11. An organic light emitting diode, comprising:
a first electrode;
a second electrode facing the first electrode;
a first emissive material layer disposed between the first and second electrodes;
a second emissive material layer disposed between the first emissive material layer and the second electrode; and
an electron blocking layer disposed between the first electrode and the first emissive material layer,
wherein the first emissive material layer and the second emissive material layer each comprise a first compound and a second compound,
wherein the second compound includes an organic compound having a structure of the following chemical formula 1 or chemical formula 3,
wherein a level of the second compound in the first emissive material layer is higher than a level of the second compound in the second emissive material layer,
wherein the electron blocking layer includes an organic compound having a structure of the following chemical formula 5 or chemical formula 7,
wherein when the second compound is an organic compound having a structure of chemical formula 1, the electron blocking layer includes an organic compound having a structure of chemical formula 7, and
and wherein, when the second compound is an organic compound having a structure of chemical formula 3, the electron blocking layer includes an organic compound having a structure of chemical formula 5:
[ chemical formula 1]
Figure FDA0002692335400000091
Wherein R is1And R2Each independently is hydrogen or C1-C20An alkyl group; and n is an integer from 0 to 4;
[ chemical formula 3]
Figure FDA0002692335400000092
Wherein R is11And R12Each independently is hydrogen or C1-C20An alkyl group; r13Is unsubstituted or substituted C8-C30Condensed heteroaryl, unsubstituted or substituted C6-C20Aromatic amino group or unsubstituted or substituted C3-C20A heteroaromatic amino group, wherein the fused heteroaryl group includes at least one of a carbazolyl moiety, an acridinyl moiety, a phenazinyl moiety, and a phenoxazinyl moiety;
[ chemical formula 5]
Figure FDA0002692335400000101
Wherein R is21To R23Each independently is unsubstituted or substituted C6-C30Aryl or unsubstituted or substituted C3-C20A heteroaromatic amino group;
[ chemical formula 7]
Figure FDA0002692335400000102
Wherein R is31Is unsubstituted or substituted C6-C20An aryl group; r32And R33Each independently is hydrogen or a substituted or unsubstituted carbazolyl group, wherein R is32And R33Is a carbazolyl group; r34And R35Each independently hydrogen, unsubstituted or substituted C1-C10Alkyl, unsubstituted or substituted C6-C20Aryl, or unsubstituted or substituted C3-C20A heteroaryl group; and p and q are each an integer of 0 or 1.
12. The organic light emitting diode of claim 11, wherein the second compound is present in the first emissive material layer in an amount from about 5 wt% to about 35 wt% and the second compound is present in the second emissive material layer in an amount from about 40 wt% to about 50 wt%.
13. The organic light emitting diode of claim 11, wherein a thickness of the first emitting material layer is thinner than a thickness of the second emitting material layer.
14. The organic light emitting diode of claim 11, wherein the organic compound having the structure of chemical formula 1 includes any one selected from the group consisting of:
Figure FDA0002692335400000111
Figure FDA0002692335400000121
15. the organic light emitting diode of claim 11, wherein the organic compound having the structure of chemical formula 3 includes any one selected from the group consisting of:
Figure FDA0002692335400000122
Figure FDA0002692335400000131
16. the organic light emitting diode of claim 11, wherein the organic compound having the structure of chemical formula 5 includes any one selected from the group consisting of:
Figure FDA0002692335400000132
Figure FDA0002692335400000141
17. the organic light emitting diode of claim 11, wherein the organic compound having the structure of chemical formula 7 includes any one selected from the group consisting of:
Figure FDA0002692335400000151
18. the organic light emitting diode of claim 11, wherein the excited singlet energy level of the first compound is higher than the excited singlet energy level of the second compound, and the excited triplet energy level of the first compound is higher than the excited triplet energy level of the second compound.
19. An organic light-emitting device, comprising:
a substrate; and
an organic light emitting diode according to claim 1 on said substrate.
20. An organic light-emitting device, comprising:
a substrate; and
an organic light emitting diode according to claim 11 on said substrate.
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